1) The document describes improvements to packaging containers that provide reinforcement and strength. 2) The containers have a non-metallic shell and bottom each with a corrosion-resistant thin inner lining that is partly inside and partly outside the container. 3) The shell has an outer reinforcing metal covering that is folded together with the outer parts of the linings to seal the container while keeping the bottom and shell unfolded.

1. * GB784638 (A)
Description: GB784638 (A) ? 1957-10-16
Improvements in or relating to catalysts
Description of GB784638 (A)
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The EPO does not accept any responsibility for the accuracy of data
and information originating from other authorities than the EPO; in
particular, the EPO does not guarantee that they are complete,
up-to-date or fit for specific purposes.
COMPLETE SPECIFICAEON Improvements in or relating to Catalysts
We, THE BRITISH OXYGEN COMPANY
LIMITED, a British company, of Bridgewater
House, Cleveland Row, St. James's, London,
S.W.1, do hereby declare this invention, for which we pray that a
patent may be granted to us, and the method by which it is to be
performed, to be particularly described in and by the following
statement:
The present invention relates to catalysts and relates more
particularly to copper acetylide catalysts for the reaction between
acetylene and formaldehyde to form 2-butyne-1: Sdiol.
2-butyne-1 : 4iol (hereinafter referred to as butynediol) is usually
prepared by reacting acetylene with an aqueous solution of
formaldehyde in the presence of a catalyst consisting essentially of
copper acetylide. The catalyst can be prepared by reacting an aqueous
solution of a copper salt with acetylene under appropriate conditions,
removing the precipitated copper acetylide and transferring it to the
vessel in which the acetylene and the formaldehyde are to be reacted.
This procedure may give rise to difficulties in handling the free
copper acetylide (which can decompose explosively when dry) and,
moreover, it has been found that the catalyst particles are liable to
attrition during the course of reaction, so that difficulties arise in

2. separating the catalyst and the product liquor.
To obtain a more robust catalyst, it has been proposed to support the
catalyst on a porous solid medium, the procedure being to deposit the
copper salt on the support and to convert it to copper acetylide in
situ. A preferred support has been silica gel, and in order to obtain
a satisfactory catalyst, it has been necessary for the catalyst
support to be specially prepared. Catalysts have been described in
which the amount of copper held on the supw port was 1012% by weight.
It is an object of the present invention to provide a catalyst much
richer in copper than such silica gel-supported catalysts, but which
is nevertheless robust and free from the disadvantages of the
unsupported catalyst.
It is a further object of the invention to provide a simplified
procedure for the preparation of such a catalyst
Yet a further object of the invention is to provide a catalyst which
is more efficient on overall considerations.
According to the present invention, a process for the preparation of a
catalyst capable of catalysing the reaction between acetylene and
formaldehyde to form 2-butyne-1: 4-diol, comprises as a first stage
the preparation of a copper silicate material containing 15--60% by
weight of copper, by mixing the requisite proportions of a solution of
a copper salt and a solution of an alkali metal silicate, the copper
silicate material being subsequently treated with acetylene, to
convert the copper content of the material to copper acetylide.
The copper silicate may be separated, washed, and dried by heating in
air to temperatures up to 500 C. or above, or by warming to only
slightly elevated temperatures under reduced pressure. On drying it
forms cakes which can readily be broken into granules, but the
invention is not limited to the use of such material. For example, the
material may be extruded into rods or converted into other suitable
forms prior to dry ing. It can, if desired, be mixed with materials
inert in respect to the reaction between acetylene and formaldehyde
such as kaolin prior to drying, and then pelleted. If the material is
heated above about 1000 C. in the drying process, its colour may
change from light blue to black, but catalysts can be prepared from
either the blue or the black material.
It is possible, if desired, to impregnate the copper silicate material
with further amounts ol copper by immersion in a solution of a copper
salt and subsequent ignition. In this way, the copper content of the
final material can be raised, but this is not essential for the
preparation of a useful catalyst.
It is possible to convert the precipitated copper silicate into a
copper acetylide catalyst without prior separation from its mother
liquor, but this is not a preferred method of operating the process of

3. qur invention.
It is sometimes considered desirable to incorporate in the catalyst
for the reaction between acetylene and formaldehyde other materials,
generally described as " cuprene inhibitors". A particularly useful
example of such inhibitors is bismuth. In carrying out the process of
the present invention it is possible to incorporate bismuth or other
such inhibitors in the catalyst, either during the first stage of
precipitating the copper silicate material or by immersing the dry
copper silicate granules in an appropriate solution. It has, however,
been found that cuprene formation is greatly reduced when catalysts
prepared in accordance with the present invention are used as compared
with unsupported or silica gel-supported catalysts, and the use of
such cuprene inhibitors is accordingly unnecessary.
The copper silicate material may be converted into the actual catalyst
used in the reaction by suspending it in water and treating with
acetylene, the wet material subsequently being transferred to the
reactor in which the reaction between acetylene and formaldehyde is to
be effected. Alternatively and preferably the conversion may be
carried out in situ in the reactor; in this case, the copper silicate
material is added to the aqueous formaldehyde which is warmed above 60
C. and acetylene is then fed to it The catalyst so prepared is robust
In batch processes in which the catalyst is suspended in aqueous
formaldehyde and the latter reacted with acetylene under pressure, the
product liquor subsequently being separated from the catalyst which is
then re-used, the catalyst of the present invention can be used
repeatedly for a large number of successive operations. The separation
of product liquor and catalyst remains facile even after much repeated
use of the same batch of catalyst In continuous operation in which
aqueous formaldehyde and acetylene are each flowed through a bed of
catalyst, catalysts prepared according to the present invention are
much less subject to attrition, to dislodgement of copper acetylide,
or to blockages causing resistance to flow than are either unsupported
copper acetylide or copper acetylide supported on preprepared
supports.
It is a further advantage of catalysts prepared in accordance with the
present invention that a given amount of such a catalyst is capable of
catalysing the reaction between acetylene and formaldehyde to a
greater extent than the same amount of supported catalyst.
The invention is illustrated by the following examples:
EXAMPLE 1.
An aqueous solution containing 140 g. of copper nitrate (Cu(NO3)23H2O)
was added to an excess of an aqueous solution of waterglass (30%
Na2SLO,) with stirring and the precipitate was filtered, washed with
distilled water and dried at 80" C. The product contained 23.5 9o' by

4. weight of copper. It was heated to 2200 C. cooled and immersed for 20
minutes in an aqueous solution containing 305 g. per litre of copper
nitrate and 46 g. per litre of bismuth nitrate (Bi(NO,)25H2O). The
product was filtered, dried at 220t C. and was roasted at 5000 C.
until it no longer fumed. 150 g. of a black powder containing 41.2",
by weight of copper and 11.7;: by weight of bismuth were obtained.
125 g. of a black powder prepared as above were placed in a 1 litre
autoclave together with 540 g. of a 42.6$ (by weight) solution of
formaldehyde. After venting with nitrogen, acetylene was admitted at
2G atms. and 800 C. and during 5 hour, while the acetylide catalyst
was formed, the temperature was raised to 100"
C Acetylene absorption ceased after 7 hours.
During this period, 126 g. of acetylene was absorbed.
The product was filtered from the catalyst.
It was found to contain 41.6 by weight of butynediol, 10.1% of
propargyl alcohol and 0.5 ,5 of formaldehyde.
The same catalyst was re-used, using 440 g. of a 52.3or (by weight)
solution of formaldehyde, 200 g. of water and acetylene at 20 atms.
and 100" C. During 5 hours 110 g. of acetylene was absorbed. The
product was fil- tered and the resulting solution contained 300 g. of
butynediol (56.8 ,o by weight), 31 g. of propargyl alcohol (6 ), and
3.5 g. of formaldehyde (0.7'-5). The yield of butynediol on
formaldehyde was 91 % and that of propargyl alcohol 7 ?'o.
This procedure was repeated nine times without any slowing of the
reaction, deterioration in the quality of the product, or excessive
difficulty in the filtration of the reaction product from the
catalyst.
EXAMPLE 2.
Aqueous solutions of 309 waterglass (1.73 kg.) and of copper nitrate
(363 g.) were mixed and the resulting precipitate washed and roasted
at 220 C. The product contained 55.2% of copper.
65 g. of this material was used in the preparation of the acetylide
and a similar procedure was followed to that of Example 1.
Almost identical results were obtained.
EXAMPLE 3.
Copper silicate was prepared as in Example 2, but instead of the
roasting at 220 C., it was heated at 1200 C. for 8 hours before being
converted to copper acetylene and used in the acetylene-formaldehyde
reaction. In operation this catalyst gave results substantially
similar to those of Example 1.
What we claim is : -
1. Process for preparation of a catalyst capable of catalysing the
reaction between acetylene and formaldehyde to form 2-butyne-1 :4

5. * GB784639 (A)
Description: GB784639 (A) ? 1957-10-16
Improvements relating to packaging containers
Description of GB784639 (A)
COMPLETE SPECIFICATION
Improvements relating to Packaging Containers
I, ALFONS MAUSER, of German Nationality, personally responsible
partner of the firm
MAUSER I(OMMANDIT-GESELLSCHAFT, of
Marienstrasse 28/30, IColn-Ehrenfeld, Germany, do hereby declare the
invention, for which I pray that a patent may be granted to me, and
the method by which it is to be performed, to be particularly
described in and by the following statement:-
This invention relates to packing containers, for instance casks or
drums, intended especially for sensitive or corrosive contents, which
drums may be provided with an entirely removable cover or may be
closed by means of a bung.
Packing containers made of different materials are known per se, for
instance containers made of cardboard and provided with metal or
plastic linings. Preferably metal foil is secured to the inner surface
of the container and, if necessary, also included in the joint between
the bottom and the shell of the container, that is to say the wall
extending from the bottom to the top of the container.
The latter step is taken in cases where the lining is inserted
loosely.
It has been found that such containers do not stand up to the stresses
encountered in practical use. The thin metal or plastic sheets tear
under the action of violent shocks so that the contents can run out or
become useless.
If the inner lining of the container is made too thick, this increases
the cost of manufacture to such an extent that the users hesitate to
employ such casks.
The invention consists in a container having a non-metallic shell and
a non-metallic bottom each provided with a respective

6. corrosion-resistant thin inner lining disposed partly inside and
partly outside the container, in which the shell is provided with a
reinforcing outer covering which lies wholly outside the container and
is folded together with the parts of the linings outside the con-
tainer so as to seal the container, the bottom and shell remaining
unfolded.
In a preferred embodiment, the shell covering is made of thin steel or
other metal and the bottom is likewise provided on the outside with a
thin walled covering of steel or other metal plate. The connection of
the inner lining with the covering of the shell and bottom is effected
by means of only one external double fold, so that the cardboard shell
disposed between them has a blunt end and is securely confined.
Preferably the end connection is also surrounded by a protective or
reinforcing ring.
Such a vessel is extremely strong and fulfils all that is required of
corrosion resistant transport and storage containers.
A very thin walled inner container made of
V2A steel may be supported by the protective shell of cardboard or
alternatively plywood protected and surrounded by a thin walled outer
covering made of less costly steel or other metal. The arrangement of
the outer thin walled covering makes it possible to shrink rolling
hoops on without damaging the non-metallic intermediate shell.
Furthermore this ensures that the rolling hoop is firmly secured in
position since the intermediate shell yields during the shrinking
process. Moreover the arrangement of the outer covering offers the
advantage that fittings, for instance cask bushes, can be securely
attached. Thus the container can be formed either as a drum with a
bung or as one with a completely removable cover and with a head joint
at one end. A particular advantage of the container made of different
materials, in accordance with the invention, is the insulating effect
of the intermediate shell of non-metallic material. The latter
provides not only cold and heat insulation but also insulation of the
inner and outer shells, made of different metals, in regard to
bridging of different members of the electrochemical series and to
corrosive action.
The particularly strong construction of the packing container made in
accordance with the invention gives it a long useful life and thus
reduces packing costs so that the contents can be sold at a lower
price when such containers are employed.
The accompanying drawing is a fragmentary section through the shell
bottom and joint of a packing container made in accordance with the
invention.
The container shell 1 1, which in this instance consists, for example,
of wrapped board or other suitable non-metallic material is provided

7. with a very thin walled inner lining 12, for instance. of aluminium or
V2A steel. For further reinforcement and strengthening of the
container an outer covering 13 made of steel or oflr metal plate is
used v..lich can also be made very thin walled.
The bottom 14 may consist of cardboard, plywood or fibre. The bottom
lining 15 is also made of material correspondilla to that of the inner
lining 12 of the shell. If necessary the bottom 14 may be provided
with an outer covering, 16, for instance of steel plate. The
connection of the shell lining 12, shell covering 13, bottom lining 15
and bottom covering
16 is effected by means of only one double fold 17. The non-metallic
container shell 11 ends here and is damped by the fold connection of
the metal and steel reinforcement surrounding said shell. For
protection and reinforcement of the head edge, a closure ring 18 may
be provided, which is deformed in the usual manner for engagement by
crane hooks and for covering the bottom. The bottom 14 and shell 11
remain unfolded, as is clearly shown in the drawing.
The arrangement of this closure ring 18 makes it unnecessary, in
certain cases, to provide the bottom covering 16 so that in such cases
the single double-fold connection includes the shell lining 12, the
bottom covering 15 and the shell covering 13.
The container made of different materials in this manner does not
differ in its external appearance from the ordinary metal containers.
It has the advantage that it can be used for containing any kind of
materials, even food stuffs having a flavour that is easily impaired
or highly corrosive material S.
What I claim is:
1. A container having a non-metallic shell and a non-metallic bottom
each provided with a respective corrosion-resistant thin inner lining
disposed partly inside and partly outside the container in which the
shell is provided with a reinforcing outer covering which lies wholly
outside the container and is folded together with the parts of the
linings outside the container so as to seal the container, the bottom
and shell reinaining unfolded.
2. A container as claimed in Claim 1, in which one or both linngs are
made of metal.
3. A container as claimed in Claim 1 or', in which the shell covering
is made of metal.
4. A container as claimed in Claim 1, 2 or 3 in which the bottom is
also provided with a reinforcing outer covering folded together with
the shell covering and the linings.
5. A container as claimed in Claim 4 in which the bottom covering is
made of metal.
6. A container as claimed iil any of the preceding claims, in wiuch

8. the shell and bottom are made of wrapped board cardboard, plywood or
fibre.
7. A container as claimed in Claim 5 or 6, in which both coverings are
made of steel.
8. A container as claimed in any of Claims 4 to 7 in which the bottom
end of the shell is damped between the coverings.
9. A container as claimed in any of the preceding claims, in which a
protective or reinforcing ring covers the folded parts and has a
radially extending flange bearing against the container bottom.
10. A container as claimed in any of the preceding claims,
characterised in that rolling hoops known per se are secured to the
shell covering by being shrunk on.
11. A container having features substantially as hereinbefore
described and illustrated in the accompanying drawing.
* GB784640 (A)
Description: GB784640 (A) ? 1957-10-16
Improvements in or relating to the production of artificial sausage casings
Description of GB784640 (A)
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The EPO does not accept any responsibility for the accuracy of data
and information originating from other authorities than the EPO; in
particular, the EPO does not guarantee that they are complete,
up-to-date or fit for specific purposes.
PATENT SPECIFICATION
Incenitors: BERNARD VICTOR FOX and ROBERT GERALD Date of filing
Complete Specification Oct 14, 1955.
Application Date Oct 20, 1954.
Complete Specification Published Oct 16, 1957.
HARDIMAN 784,640 No 30244/54.

9. Index at Acceptance: -Class 2 ( 2), B 2 C 5, DZAS.
International Classification: -B 29 d D 01 f.
CO O MPLETE SP Ed T i FICATION Improvements in or relating to the
Production of Artificial Sausage Casings We, BRITISH CGELLO Pr A Nl X
LIMITED, a sion, desirable in the sausage making British Company, of
Bath Road, Bridg trade By the expression " gel state " as water,
Somerset, do hereby declare the employed in the present specification,
is invention, for which we pray that a meant the swollen,
water-containing state patent may be granted to us, and the which the
tubular structures possess when method by which it is to be performed,
to coagulated in manufacture and before be particularly described in
and by the they are dried Sausage casings consisting iolowhing
statement: wholly or mainly of an insoluble alginate,
This invention is for improvements in in the gel state normally
comprise about or relating to the production of artificial 75 % of
water by weight, based on the sausage casings weight of the gel
casing.
A method of producing artificial sausage l 3 ritish Patent
Specification No 552,770 casings has already been proposed which
describes a process for the production of comprises forming a viscous
solution of alginic acid films sufficiently strong in ani alginate,
passing said solution through the wet state to be amenable to
treatment an annular nozzle into a coagulating bath, in a high speed
transparent paper machine and allowing the formed tubular strue in
which process previously coagulated ture to set in said coagulating
bath The calcium or like insoluble alginate films coagulating bath
consists preferably of a are at least,partially dried, prior to con10
% to 15 % weakly acid calcium chloride version to alginic acid filmns
by trea Ltment solution For the purpose of bringing the in an acid
bath.
coagulation process to completion more Also, British Patent
'?pecification No.
quickly, and also of accelerating the 548,248 describes a process for
the manudehydration of the coagulated structure, facture of alginic
acid films in which the it has previously been proposed to subject
films are, dried to a state in which the the freshly precipitated
tubular structure, films contain not more than 30 % of free still
containing coagulant, to a tempera moisture followed by conditioning
in air ture above 40 C, and preferably a tlem having a relative
humidity of 65 %.
p)erature of 70 C to 80 ' C, whereupon One of the objects of the
present inventhe component that has e Crystallised out is tion is to
provide, a process for the producremoved by washing, and the said
struc tion of improved calcium alginate ture is thereupon dried, in

10. some eases sausage casings, having in the water-wet after treatment
with a plasticiser, such as condition improved mechanical properties
glycerine as compared with those of the casings in Sausage casings,
both natural and the gel state, whereby the improved casartificial,
often come on to the market in ings are rendered better adapted for
use the water-wet condition It has been in the sausage-making trade.
found, however, that although sausage Accordingly, the present
invention procasings consisting wholly or mainly of vides a process
for the production of ah an insoluble al ginate, possess manly
use:mproved water-wet calcium alginate ful properties, they are
nevertheless, when sausage casing, having in the water- wet in the gel
state, lacking in certain mechl tondition improved -nechanical
properties anical properties, such as tensile strength, as compared
with those of the casing in bursting strength, and resistance to abra
ihe gel state, which process comprises lPrice 3 s 6 d l -I 1 d 84,640
' subjecting a purified calcium alginate sausage casing, free from
water-soluble impurities, and in the gel state, to a drying treatment,
whereby its water-content is reduced to a value less than r 50 % by
weight, based oh the weight of the partially dried casing, and
thereafter rehumidifying the partially dried casing by treatment with
water until it becomes saturated.
The invention includes an improved calcium alginate sausage casing,
whenever produced by the process in accordance with the invention.
Preferably the purified calcium alginate casing, free from
water-soluble impurities and in the gel state, is subjected to a
drying treatment, whereby its water-content is reduced to a value less
than 25 %'' and preferably to a value lying within the range comprised
between 5 % and 20 %, by weight, based on the weight of the partially
dried casing.
The gel calcium alg'inate casingo, as first coagulated in manufacture,
may be freed from water-soluble impurities by thorough washing in
water.
In the preferred procedures, the purified gel calcium alginate casingo
is subjected to the drying treatment by evaporation by heat at a
temperature lying within the range between 40 ' C and 100 C., and
preferably between 80 C and 90 ' C For this purpose, the purified gel
casing may be flattened and the flattened casing may be passed over
and in contact with heated drying rollers Alternatively, the purified
gel calcium alginate casingmay be inflated with a gas under gentle
pressure, and the inflated casino may be passed through a heated
tubular drying oven, where its external surface is subjected to a
current of warm dry air, preferably in countercurrent flow Other
drying procedures will readily suggest themselves to those skilled in
the art.

11. The partially dried casing may be rehumidified to water-saturation by
treatment with liquid water, for example, by passing the partially
dried casing through a bath containing water, or by spraying the
partially dried casing with water The temperature of the water
employed lies preferably within the range between 10 C and 25 ' C,
since no noticeable adxantage has been found in departing from normal
ambient temperatures, but higher or lower water temperatures may be
employed, if desired.
The rehumidified calcium alginate sausage casing may finally be reeled
or shirred, (that is, gathered up longitudinally) or collected in any
other form suitable for despatch.
A specific method of carrying the invenlion into effeet will nonw be
descril)bel by way of illustration with reference to the following
example.
Through the present specifieation, parts and proportions are parts and
proportions by weight unless otherwise stated.
EXAMPLE I
An improved alginate sausage casing, having in the water-wet condition
improved mechanical properties as corn 75 pared with those of the
casing in the gel state, was produced In the followiing way:A viscous
aqueous solution of sodiumt alginate was prepared by stirring 40 lbs
80 of granular sodium algiinate, of the kind sold by Alginate
Industries Limited under the designation W 1 OS, into 960 lbs of water
at 20 C, and continuing agitation until solution was complete The
solution 85 was deaerated by standing for 24 hours in a closed vessel
under a reduced pressure of 22 inches of mercury, and the deaeraled
solution was filtered through 120 mesh metal gauze 90 The filtered
viscous aqueous solution of sodium alginate was passed under pressure
to an extrusion,malchine The aluinate solution was metered by means of
a metering pump before bleing' extruded thlrough 95 an annular orifice
into a coagulating b)ath having a temperature of 20 C atd consisting
of an aqueous solution containilng 11 %', of calcium chloride and O O
{, of hydrochloric acid The solution extruded 100 tlirough the annular
orifice was coagulated on enteringo the bath, wherebov a solidified
tubular structure was formed The tubular structure formed was then
imminersed for hours in a bath having a temperature of 105 C and
consisting of an aqueous solution containing 227; of calcium chloride
to complete the conversion of the tubular structure by double
decomposition of the sodium alginate with the calcium chloride 110
with the formation of water-insoluble caicium alginate and
water-soluble sodium chloride The fully coago latld gel calciulm
alginate sausage casing thus obtained wa, then purified by wavahing
thoroughxly with 115 water having a temperature of 420 C, until the
casino', thus treated, was free fronm iater-soluble ihlpu Iities.

12. The purified calcium alginate sauae casing, free fromnt water-soluble
impurities 120 and in the gel state, was thereupon subjected to a
drying' treatment, by fiattening' the casing and passing the flattened
casingo over and in contact with drying rollers heated to 70 C,
whereby the 125 water-content of the easing was reduced from its
initial value to a value of,91; weight based on the weighit of calcium
alginate plus water contained in the parjected to a drying treatment,
whereby its water-content is reduced to a value less than 2,5 o by
weight, based on the weight of the partially dried casing.
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* GB784641 (A)
Description: GB784641 (A) ? 1957-10-16
Neutron well logging apparatus
Description of GB784641 (A)
COMPLETE SPECIFICATION
Neutron Well Logging Apparav
We, SCHLUMBERGER WELL SURVEYING
CORPORATION, a Corporation organised under the laws of the State of
Texas, United
States of America, of 5000, Gulf Freeway,
Houston, County of Harris, State of Texas,
United States of America, do hereby declare the invention, for which
we pray that a patent may be granted to us, and the method by which it
is to be performed, to be particularly described in and by the
following statement :
This invention relates to neutron well logging apparatus and, more
particularly, pertains to a new and improved neutron generator

13. especially adapted to traverse the narrow confines of a well or bore
hole, although useful in a variety of other applications.
Since a neutron generator embodying the present invention is ideally
suited to the needs of well logging service, it will be described in
that connection.
It has been proposed heretofore that a generator of high energy
neutrons be employed in neutron-gamma ray or in neutron-neutron
logging. As contrasted with a radium- beryllium source conventionally
utilized for such logging, a neutron generator may feature a
negligible amount of radiation other than the desired neutrons, a
higher yield of neutrons, a controlled yield of neutrons, neutrons at
higher energy than formerly possible, mono-energetic neutrons and
control of the generator source to permit its deactivation prior to
withdrawal from a well. The first five of these attributes are
important in obtaining more informative logs, whereas the last is
valuable in minimizing health hazards to operating personnel.
In general, prior neutron generators were only suited for laboratory
use and were not designed to meet the severe requirements imposed on
well logging equipment. Thus, presently available neutron generators
are much too large to be passed through a borehole.
The components are not adaptable to the source-detector spacing
requirements of well logging. Moreover, these neutron generators are
too critical in their operation and too fragile for logging service.
It is, therefore, a primary object of the present invention to provide
an improved neutron generator which meets all requirements of logging
service.
A particular object of the present invention is to provide an improved
neutron generator which is small enough to permit its introduction
into an inherently cylindrical borehole.
Another; object of the present invention is to provide an improved
neutron generator which may be reliably operated during a logging run
without requiring critical and continuous operating adjustments.
An additional object of the present invention is to provide an
improved neutron generator which may be reliably operated at the high
ambient temperatures encountered at depth in logging operations.
Yet another object of the present invention is to provide an improved
neutron generator that is rugged enough to operate effl ciently and
reliably although subjected to the severe physical shocks usually
imposed on logging apparatus. during transport to and from a well
location, as well as during a logging run.
These and other objects of the present invention are obtained by
providing a neutron generating system comprising a sealed envelope
containing a gas and including an ionsource section and an
accelerating-gap section, a target for intercepting the accelerated

14. ions of the gas, said target being adapted to react with the ions of
the gas to produce neutrons, characterised by a sealed off conduit
connecting said ion-source section with said accelerating-gap section
and constituting a closed and sealed loop between said sections of
said envelope.
More specifically, the generator comprises an envelope containing a
gas such as deuterium. An anode and a cathode are supported within the
envelope and a magnet is employed to provide a magnetic field
component for effectively increasing the path of electrons travelling
between the anode and cathode. Thus, a continuous ionic discharge
occurs and the portion of the generator thus far described operates as
a source of ions.
A probe of the accelerator, which effectively reaches into the region
of the ion source, removes positive ions from the source and a
suitably high potential difference is impressed between the probe and
the target so that these positive ions are accelerated to the required
high velocity prior to striking the target. The target includes a
material containing an isotope of hydrogen, for example, tri- tium.
From the resulting deuterium tritium reactions, neutrons are derived.
The target may be comprised of a metal having a lower melting
temperature than its hydride. Thus, an alkali metal, such as lithium,
may be combined with tritium and the resulting hydride employed as a
target.
In operation, after tritium is used in the deuterium-tritium reaction,
the remaining lithium in each molecule melts away or evaporates at the
operating temperature of the target to expose a fresh hydride surface.
The generator may also include a plurality of deflection plates
supported within the envelope in a region between the ion source and
the probe. By suitably energizing these deflection plates, the ion
beam may be caused to traverse a desired path on the target, thereby
to prevent depletion or burn out of a localized spot.
In order to maintain the neutron flux emanating from the target within
prescribed limits, a detector-integrator may be employed to derive a
control potential representing a characteristic of the neutron flux,
such as the number of neutrons counted per unit time.
This potential is employed to adjust the number of ions drawn from the
ion source by the probe, thereby effecting automatic control of the
neutron output since the yield is dependent upon the number of
positive ions incident on the tritium target.
The apparatus may further include a control system for maintaining the
ion concentration of deuterium gas in the ion source at a preselected
value despite the fact that ions of the gas are continuously
withdrawn. The system comprises a current-limiting, or constant
current, device connected in series circuit relation with the anode

15. and cathode of the ion source. Thus, although the pressure within the
ion source may vary so as to alter the circuit impedance of the
source. the voltage drop across the current-limiter varies so as to
maintain the circuit current constant.
Accordingly, the ion concentration within the ion source remains
constant.
The control system further operates automatically in response to the
ionization current to adjust the amount of gas issuing from a
deuterium supply. The deuterium supply preferably may be a material
containing the gas and enclosed by the anode of the ion source.
Accordingly, deuterium gas may be ionized almost immediately upon
emanation. In addition, the control system may respond to the
ionization current in adjusting the gas-absorption rate of a gas
absorber.
Because the neutron generator is a closed contiguous system, it is
necessary to balance two opposing requirements. The gas pressure in
the ion source must be high enough to allow sufficient ionization to
be produced to give adequate ion current for its operation.
However, the gas pressure must be low enough to avoid appreciable
production of ionization in the accelerating gap. A stable balance may
be achieved by constructing these two components so that the
mean-lree- path in the ion source is large compared to the
mean-free-path in the accelerating gap.
As used herein, the term i' mean-freepath" denotes Ble average
distance that electrons travel in a particular gas between collisions
with atoms or ions of that gas. If a sufficient number of such
collisions take place, the ionization produced is cumulative,
resulting in a continuous ionic discharge.
The spacing between electrodes of the accelerating gap is made small
enough to minimize the path travelled by electrons in this region. In
this way, ionization is inhibited despite the extremely high
acceleration potential applied to the gap.
The spacing between electrodes in the ion source is made large enough
to maximize the path of travel of electrons and thereby assure the
occurrence of strong ionization. In addition, the auxiliary magnetic
field in the ion source causes electrons to describe nonlinear paths,
such as spirals, in order to extend effectively the path of travel.
To assist in maintaining strong ionization in the ion source while
inhibiting ionization in the accelerating gap, the generator may be
provided with a conduit external of the en velope for fluidly
connecting the accelerating gap region with the ion source region and
associated with a pump. The pump is arranged to produce a flow of gas
through the conduit in a direction from the accelerating gap toward
the ion source and thereby maintains a minimum pressure in the gap at

16. the same time maximum pressure is produced in the source. - Preferably
The pump is of The type wherein The gas is ionized and flow is
effected by means of a series of suitably-energized electrodes.
A strong, rugged neutron-generating device is afforded by supporting
various electrodes of the device on support rods which extend
longitudinally through its envelope.
These rods are enclosed by 'sleeves of electrically insulating
material, and electrically insulating spacers maintain such electrodes
in proper spatial relationship.
The novel features of the present invention are set forth with
particularity in the appended claims. The present invention both as to
its organization and manner of operation, together with further
objects and advantages thereof, may best be understood by reference to
the following description taken in connection with the accompanying
drawings in which:
Figs. 1A, 1B and 1C illustrate schematically the upper, middle and
lower portions, respectively, of neutron well logging apparatus
embodying the present invention;
Fig. 2 is an enlarged, perspective view of the neutron generator
illustrated in Fig. 1B, portions of the device being shown broken away
and in section to reveal various interior details thereof;
Figs. 3 and 4 are partial cross-sectional views taken along lines 3-3
and W4 respectively, and drawn to an enlarged scale of
Fig. 2;
Figs. 5 and 6 are electrical circuit diagrams illustrating the details
of certain of the elements shown in Fig. 1A;
Fig. 7 features a series of curves representing certain operating
characteristics of the circuit shown in Fig 6 and which are useful in
explaining its operation;
Fig. 8 is an enlarged longitudinal view, shown partly cut-away and in
section, of an ion pump suitable for use in association with the
neutron generator shown in Fig. 2; and
Fig. 9 is a cross-sectional view taken along lines 9-9 of Fig. 1B and
drawn to an enlarged scale.
In Fig. 1A of the drawings, the neutron well logging apparatus
embodying the present invention is shown disposed in a bore hole 10
traversing a plurality of earth formations 11. Bore hole 10 usually
contains a hydrogenous drilling liquid 12, such as a water base or oil
base mud, and it may be lined with one or more strings of metallic
casing (not shown) or it may be uncased, as illustrated.
The neutron well logging apparatus may comprise a pressure-resistant
housing 13 enclosing a neutron generator 14 (Fig. 1ZB), a radiation
responsive device 15(Fig. iC) for detecting the phenomena to be
observed, and associated electronic equipment required for proper

17. operation of the neutron generator and the detector, as described in
greater detail hereinafter.
A shield plate 16, disposed above detector 15, may be employed to
shield the detector from radiation emanating from generator 14.
If the apparatus is to be used for obtaining neutron-gamma ray logs,
the shield may be composed of lead, and if neutron-neutron logs are
desired, the shield may be constructed of a boron compound, such as
boron carbide imbedded in paraffin. Of course, a composite sheet of
lead and boron loaded paraffin may be utilized if suitable detectors
are included for obtaining both types of logs simultaneously or
successively.
Housing 13 is suspended in the bore hole by means of an armored cable
17 which, in connection with a winch (not shown) located at the
surface of the earth is utilized to lower and raise the apparatus in
the bore hole in a customary manner. As will be later described in
detail, cable 17 comprises a plurality of insulated conductors that
electrically connect the apparatus within housing 13 with surface
equipment 18.
The neutron generator 14 (Fig. 1B) is suitably supported by a
conventional shock mounting (not shown) within housing 13. The
generator comprises an evacuated envelope 19, preferably constructed
of out-gassed pyrex glass, and filled with deuterium gas under a
selected pressure which may be ira the neighborhood of 1 to 10 microns
of mercury.
As best seen in Fig. 2, envelope 19 encloses the elements of an ion
source 20 and an accelerating gap 21. Source 20 includes upper and
lower metallic cathode electrodes 22 and 23 of disc-lilte
configuration supported in spaced, parallel relationship. Disc 22 is
provided with a plurality of openings 24 distributed about an annular
path and spaced radially from the center of the disc, whereas disc 23
includes a central aperture 25 positioned in coaxial alignment with
envelope 19.
Ion source 20 further includes a metallic anode electrode 26 supported
between cathodes 22 and 23 and comprised of a hollow, cylindrical
member 27 terminated by upper and lower plates 28 and 29 provided with
respective openings 30 and 31. These openings have a diameter somewhat
greater than the diameter of aperture 25 and the anode 26 is
positioned so that cylinder 27 and the openings 30 and 31 are in
coaxial alignment with envelope 19. An annular metal plate 32 having a
central opening 33 receives cylinder 27 and is mechanically and
electrically connected thereto.
A cylindrical member 34 of magnetic material, such as an alloy of
aluminum, nickel and cobalt, commonly referred to as alnico, has a
generally cylindrical opening 35 which receives envelope 19. Its

18. position and longitudinal length are such that it is essentially
co-extensive with cylinder 27 of anode 26. Member 34 is permanently
magnetized so that its upper and lower ends are of oppo- site magnetic
polarity, thereby establishing an axial magnetic field within envelope
19.
The strength of this magnetic field is pre selected, in view of the
spacing between anode 26 and cathodes 22, 23 to achieve a
mean-free-path for electrons which move spirally due to the field,
sufficient to promote strong ionization of the deuterium gas within
envelope 19. For example, a strength of 500 gauss with an electrode
spacing of 3 inches has been found suitable. If desired, a pellet (not
shown) of radioactive material.
such as radium, may be associated with ion source 20 to initiate
ionization of the gas.
Accelerating gap 21 is comprised of a metal probe 36 of generally
cylindrical configuration having a lower, hemispheric opening 37
terminating in a central aperture 38 coaxially aligned with
non-conducting envelope 19. The lower portion of envelope 19 is flared
inwardly to form a re-entrant, conelike, tubular section 39 which
terminates at and is sealed to a metal target 40 of hemispheric
configuration and constructed of an alloy of nickel, cobalt, manganese
and iron.
The spacing between target 40 and the surface of opening 37 in probe
36 is smaller than the mean-free-path. Thus, ionization of deuterium
gas does not occur although these electrodes are suitably energized
for operation as an accelerating gap for the deu- terium ions.
Target 40 preferably is plated with a layer 41 of zirconium, or other
hydrogen-absorb- ing metal, which is hydrided in a well-known manner
with tritium. For example, the zirconium layer may be alternately
heated and cocled in an atmosphere of this isotope of hydrogen. Of
course, deuterium may be employed for this purpose if a
deuteriumdeuterium reaction is desired instead of a deuterium-tritium
reaction.
The neutron generator further includes a plurality of metal deflection
plates 49-45 positioned between cathode plate 23 and probe 36. These
deflection plates are oriented with respect to the longitudinal axis
of envelope 19 so that ions traversing a path between apertures 25 and
38 may be deelected in two dimensions, thereby to control the point at
which such ions impinge on target layer 41. Moreover, as will be
pointed out more particularly hereinafter, these plates may be
employed to control the focus of the beam of ions striking the target.
Each of deflection plates 49-45 is supported by a respective one of
electrically conductive strips 46-49. Each strip extends from its
deflection plate in a radial direction relative to the longitudinal

19. axis of envelope 19 and is supported by, but insulated from, probe 36
on a pair of similar mountings 50.
For example, as shown in Fig. 3, mounting 50 comprises a bolt 51
threaded into an opening 52 in the upper side of probe 36.
The body of bolt 51 is received by a thin, insulating tube or sleeve
53 which may be constructed of out-gassed glass and which, in turn; is
received by another thin, out gassed glass tube 54. The lower
extremities of tubes 53 and 54 terminate at the upper surface of probe
36. while the upper extremity of tube 54 terminates at the under
surface of strip 46. Strip 46 is provided with an opening 55 which
receives tube 53.
and this tube terminates at the upper surface of strip 46. A glass
washer 56 is interposed between the upper surface of strip 46 and head
57 of bolt 5l so that although the bolt may be thightened to secure
strip 1'} wiTh respect to probe 36. tlie blt 5! is e;ectrically
insulated from the strip. SIoreo-er, since the strip is firmly clamped
between the under surface of washer 56 and the upper end of outer tube
54, a rigid mechanical connect tion is achieved.
To maintain the electrodes 36 3' and 22 in proper longitudinally
spaced relationship, a pair of long metallic rods 58 and 59 and a
suitable spacer arrangement are provided. As shown in Fig. 3. rod 58
passes through an opening 60 in support strip 46 and its head 61
mechanically and electrically contacts the under side of this strip.
An inner sleeve 62 of an electrically insulating material. such as an
out-gassed glass tube, extends between the upper surface of strip 46
and the upper surface of cathode plate 22.
passing through aligned openings in the plates 23, 32 and 22. These
openings have a diameter smaller than the outer diameter of a
plurality of insulating spacers 63, 64 and 65. constructed of thin
out-gassed glass tub- ing. Spacer 63 extends between the upper surface
of strip 46 and the lower surface of disc 23, spacer 64 extends from
the upper surface of disc 23 to the under side of plate 39. and spacer
65 likewise extends between plate 32 and disc 22. An insulating washer
66, which may be constructed of out-gassed glass. separates and
electrically insulates a nut 67 from cathode disc 22. The nut 67 is
threaded to rod 58 and may be thightened in order to bind the several
elements into a rugged unitary assembly.
Rod 59 is arranged in a manner similar to rod 58. but as shown in Fig.
4, its lower extremity is threaded into an opening 68 in probe 36. It
is received bv a long. thin glass sleeve 69 which in turn. receives a
series of glass spacers like the one designated 70 extending between
the upper surface of probe 36 and the lower surface of cathode plate
23.
Its upper end is provided with an arrangement similar to insulating

20. washer 66 and nut 67 by means of which several elements uiav be bound
in place.
The upper extremities of rods 58 and 59 extend through a conventional
header 71 which closes envelope 19. The usual type of pressure-tight
seals are employed for these leads as well as the remaining metallic
leads 72-81. Thus, connections may be introduced to the several
elements within non-conducting envelope 19.
Lead 72 is connected at its lower end to cathode disc 23 and is
provided with a thin sleeve cf insulating material. It passes through
an opening (nct shown) in plate 32 and an aligned opening 82 in
cathode plate 22. Similarly, leads 74. 75, 76 and 79 are electrically
connected to support strip 47 for deflection plate 43, support strip
48 for deflection plate 44, anode plate 32, and support strip 49 for
deflection plate 45, respectively. Of course, each is provided with an
insulating sleeve so that no electrical connections are made at the
points at which it passes through aligned openings in others of the
electrodes. Lead 73 is directly connected to the uppermost cathode
disc 22.
Leads 77 and 78 are enclosed by individual glass sleeves, and after
passing through respective openings in cathode plate 22, are connected
to the ends of a filament winding 83 which is imbedded in a
cylindrical layer 84 of deuterium-emitting material coated on the
inner wall of cylinder 27. Layer 84, for example, may comprise a
mixture of granulated zirconium deuteride and a suitable refractory
material. Thus, as the temperature of the layer increases due to
energization of filament 83, the pressure of deuterium over the
surface of the layer increases. Layer 84 is so loaded with deuterium
that when heated by filament 83 to a temperature in the range from 900
C. to 3509C., deuterium is emitted.
Another filament 85 is supported by leads 80 and 81 in the portion of
envelope 19 bounded by header 71 and cathode plate 22.
This filament is composed of an absorber material such as zirconium
and is arranged so that, at a temperature in the range from 3505C. to
450"C., gas is absorbed.
A lead 86 extending through re-entrant envelope section 39 is soldered
or welded to target 40. It passes through a U-shaped guide 87 which is
secured to one side of reentrant section 39.
In order to maintain probe 36 in coaxial alignment with envelope I9,
an annular centering member 88 is fixed to the periphery of the probe.
Member 88 comprises a plurality of curved fingers 89 of a resilient
material which flexibly engage the inner surface of the envelope 19.
Such a non-rigid connection permits a small degree of relative
movement between the probe end of the electrode assembly and the
envelope.

21. Neutron generator 14 is provided with a conduit 90 connected at one of
its ends to the lower extremity of envelope 19 by an annular seal 91.
The other end of conduit 90 is connected to header 71 by an annular
seal 92. A pump 93, such as a conventional diffusion pump, a
mechanical pump, or one of the type to be later described in
connection with Fig. 8, is interposed in conduit 90 and operates to
move gas in the general direction of arrow 94.
An auxiliary, ring-like electrode 95 is disposed in the vicinity of
junction 91. It is supported by a thin conductive rod 96 which depends
from probe 36. The spacing between auxiliary electrode 95 and target
40 is arranged to inhibit ionization which might otherwise occur due
to the long path for electrons travelling from target 40 through tube
90 to cathode plate 22.
Opening 35 of magnet 34 is provided with a cut-cut 97 to permit the
passage of tube 90. Thus, the magnet may simply be slipped over the
assembly of envelope 19 and tube 90.
In constructing generator 14, the usual precautions observed in the
fabrication of discharge devices are observed. For example, metal
materials for the various electrodes are selected so that there is
relative freedom from gases that may be absorbed prior to, or during,
the fabrication process, and which may be later expelled in operation
te contaminate the generator. Moreover, with the exception of the
elements of the ion source, the electrode metals may be selected on
the basis of low secondary-elec- tron-emission characteristics to
minimize the possibility of breakdown. Alternatively, an easily
out-gassed metal may be employed if coated with a thin layer of
material of low thermal emissivity. Electrodes of the ion source may
be constructed of nickel or an alloy of nickel and chromium, or any
other metal providing good secondary emission to aid ionization. The
original out-gassing is accomplished by a conventional tube (not
shown) which projects externally of header 71. The required amount of
deuterium is introduced through the tube before it is sealed.
-Referring now to Fig. 1A, in order to provide power for operating
generator 14 and its associated circuitry, and yet remain within the
voltage- and current-carrying capabilities of conductors in cable 17,
power is supplied by a single-phase center-tapped source 100 of
alternating current located at the surface of the earth in equipment
18. For example, source 100 may provide 600 volts at 400 cycles at
conductors 101 and 102 which are connected via an operating switch 103
to conductors 104, 105, 106 and 107 of cable 17, arranged to provide
parallel, tvvo-vere lines. To ascertain that the voltage between any
of the conductors 104-107 and a shield 108 of cable 17 does not exceed
approximately 300 volts, shield 108 is connected by a conductor 109
and switch 103 to a centertap lead 110 of source 100 which is at a

22. point of equal potential with respect to leads 101 and 102;
Paralleled leads 104, 106 and 105, 107 are connected to the primary
winding of a step- down transformer 111 mounted within housing 13. The
primary winding of transformer
111 is center-tapped and is connected by a lead 112 to shield 108 and
to housing 13.
Under normal load conditions for the operation of neutron generator 14
and its associated circuits, the voltage applied to the surface end of
cable 17 is materially reduced due to the conductor resistances before
reaching the housing end of the cable.
Accordingly, a voltage of approximately 300 volts is applied to the
primary winding of transformer 111 and the turns ratio of this
transformer is arranged so that a voltage in the neighbourhood of 115
volts is available at conductors 113 and 114. Of course, the
transformer may be of any well-known adjustable type so that the
required voltage output may be derived.
Leads 113 and 114 extend longitudinally through housing 13 and, as
shown in Fig.
1B, are connected to a medium-voltage power supply 115. Supply 115
provides a unidirectional output of approximately 1500 volts and its
output terminals are shunted by a voltage-dividing resistor 116. The
positive terminal of the supply is grounded to housing 13 and its
negative terminal is connected to lead 59 which extends to probe 36 of
generator 14. A tap 117 of voltage divider 116, at approximately 100
volts from the negative terminal of supply 115, is connected to the
lead 72 which extends to cathode 23 of ion source 20. Another tap 118,
displaced approximately 25 volts from tap 117 in a positive direction,
is connected by lead 73 to cathode 22 of the source. To complete the
circuit for ion source 20, anode 26 is connected by leads 76 and 119
to a currentlimiting variable impedance in a control circuit 12 leads
81 and 82 to the secondary winding of another step-down transformer
138. One terminal of the primary winding of each of transformers 137
and 138 is connected to power lead 114 and the remaining terminals of
these transformers are connected via leads 139 and 140, respectively,
to pressure control circuit 120 (Fig. lea). As will be described in
detail in connection with Fig.
6, pressure control circuit 120 comprises a repay device for
selectively connecting either of leads 139 and 140 to power lead 113
in response to the current which flows in the anode-cathode circuit of
ion source 20. That is, when this current tends to increase due to an
increase in pressure in envelope 19, above a first value, transformer
138 is energized so that gas is absorbed by filament 85. Conversely, a
decrease in pressure causes the deenergization of filament 85, and
when the pressure goes below a second value lower than the first, the

23. energization of transformer 137 occurs and filament 83 emits
deuterium.
The portion of the well logging apparatus thus far described relates
to the generation of neutrons for irradiating formations 11. In order
to obtain a log, for example, of the resulting gamma radiation, means
are provided for energizing detector 15 (Fig. 1C) and for recording a
characteristic of its output.
To this end, a source of alternating current 150 in surface equipment
18 is coupled to a transformer 151 having one terminal connected to
grounded shield 108 and the other terminal connected via an isolating
choke 152 to a conductor 153 of cable 17. Conductor 153 traverses
housing 13 and it is connected to the housing via the series-connected
primary windings of transformers 154 and 155. Transformer 154 is a
power transformer for a conventional power supply 156 having its
negative output terminal connected to housing 13. Power supply 156
develops the high voltage for operating tube 15 applied thereto over
an isolating resistor 157. The remaining terminal of tube 15 is
connected by a lead to housing 13. The junction of resistor 157 with
the lead to tube 15 is connected by a coupling condenser 158 to the
input circuit of a conventional pulse amplifier 159. The input circuit
of the amplifier is completed by a suitable connection to housing 13,
and a voltage of proper magnitude for operating the amplifier is
derived from power supply 156 over a lead 160.
Transformer 155 is a pulse transformer to which the output signal of
amplifier 159 is applied.
This output signal is derived at surface equipment 18 by a pulse
transformer 161.
The primary winding of the transformer is connected to a filter
including a series condenser 162 and shunt choke 163 for attenuating
voltages at the frequency of source 150.
The transformer's secondary winding is connected to a conventional
integrator and recording unit 164. Unit 164, for example, may comprise
a capacitor for deriving a potential representing the number of pulses
applied per unit time and a recording voltmeter to which this
potential is applied. The recording medium of the voltmeter is
displaced in a customary manner in synchronism with movement of
housing 13 through bore hole 10 so that a continuous log may be
obtained.
In operation, housing 13 is lowered into bore hole 10 prior to closing
switch 103.
Thus, operating personnel are shielded from any dangerous radiation
emanating from neutron generator 14 by the earth formations 11 and
drilling fluid 12.
With switch 103 closed, power supply 115 energizes ion source 20 (Fig.

24. 1B) and electrons spiral. due to the influence of magnet 34, from
cathodes 22 and 23 toward anode 26. Strong ionization of the gas
within anode 26 thus occurs and, in the ensuing continuous ionic
discharge, great numbers of positive ions of deuterium are produced.
By reason of the manner in which cathodes 22 and 23 are connected to
voltage divider 116, cathode 23 is at a negative potential with
respect to cathode 22 and an ionic drift occurs through ion source 20
in the general direction of cathode 23. Some of these positive ions
pass through opening 25 in cathode 23 and, assuming that deflection
plates 4245 are impressed with an average potential that is negative
with respect to cathode 23, ions are drawn by these plates in the
direction of probe 36. This flow of ions is assisted by the negative
potential of probe 36 relative to deflection plates 42-45 and some
ions pass through opening 38 in the probe.
Since power supply 126 impresses a high potential between the probe
and target 40, positive ions are accelerated to very high velocities
prior to striking target material 41.
The highly accelerated positive deuterium ions thus react with the
tritium in the target material and neutrons of energies in the
neighborhood of 14 million electron volts are generated.
Since ions, prior to acceleration, are under the influence of the
electrostatic field produced by deflection plates 42-45, the ion beam
does not impinge on target material 41 at a single point. Instead, the
applied voltages, which are displaced in phase by 90 , cause the beam
to traverse a circular path on the target material. By thus
distributing the ion beam over a larger area of the target, localized
heating and burn-out of the target material is prevented. Of course,
if desired, a suitable frequency multiplier may be substituted for
phase shifter 99 so that patterns having a configuration other than a
circle may be described on target material 41 in a known manner.
Positive ions upon striking target material 41 produce secondary
electrons which are accelerated across gap 21 in the direction
opposite to ion travel. Most of these electrons pass through openings
38, 25, 31 and 30, traversing ion source 20 without collision, and
strike cathode 22. If desired, a plate (not shown) constructed of a
refractory material of low atomic number, such as quartz or beryllium
oxide may be positioned in the path of such electrons at plate 22. The
electrons thus may be prevented from striking cathode 22 where they
might undesir- ably cause localized heating and the emanation of
absorbed gases. In addition, such a plate may serve to prevent
possible recombinations of electrons and ions at the surface of the
cathode.
High energy neutrons emanating from target material 41 irradiate
formations 11 as well as detector 127. A small fraction of the

25. incident neutrons produce recoil protons in the hydrogenous lining of
the detector. Some of these protons cause ionization in the gas of the
detector and the resulting pulses are amplified and integrated in
stage 131. Thus, a control potential is developed and applied to
output control circuit 123 which controls the relative average
potential between cathode 23 and deflection plates 42-45. If the
neutron flux increases, the number of counts per second increases and
output control circuit 123 reduces the potential between cathode 23
and deflection plates 4-45 so that fewer ions are drawn from source 20
toward accelerating gap 21, thereby decreasing the neutron flux.
Conversely, a decrease in the neutron flux causes an increase in the
negative voltage applied between cathode 23 and deflection plates
42-45. In this way, the neutron flux remains substantially constant
over a wide variety of operating conditions.
Control system 120 serves two important functions. In the first place,
it maintains the ion concentration within the plasma of the continuous
ionic discharge in ion source 20 essentially constant. This is
accomplished by the current-limiting impedance (not shown) that is in
series with the anode and cathode of the source. Thus, if the anode-
cathode current tends to increase, the current-limiter effectively
reduces the potential across the ion source. This reduces the
ionization current and the ion concentration is not permitted to rise.
Conversely, an increase in the potential across the ion source 20
accompanies a tendency toward decreasing current.
In the second place, if the gas pressure within envelope 19 decreases
below a prescribed limit and the ion source current does decrease, a
relay (not shown) of circuit 120 completes an energization circuit for
transformer 137, thereby heating filament 83. This filament heats
material 84 to its deuteriumemitting temperature. Above this limit,
filament 83 is de-eneroizedt and if the gas pressure increases beyond
a selected, higher value, the relay mechanism of circuit 120 energizes
tranrformer 138. Thus, absorber filament SS is heated to its operating
temperature. It is evident that the pressure within envelope 19 may be
mah.tained constant at a desired value.
Pump 93 operates continuously so that gas is drawn through tube 90 in
direction 94 from accelerating gap ?l toward ion source 20.
Accordinglyz the pressure in The ion source is maintained sleight'
higher than in the accelerating gap. This pers ts a greater efficiency
in the formation of ions in the ion source, while reducing the
possibility of breakdown in the accelerating gap.
Irradiation of the formations 11 by the neutrons produced in generator
14 results in nuclear radiation that is incident on detector tube 15.
The detector responds to gamma rays and its output is in the form of
pulses which are amplified in stage 159 before being fed to the

26. integrator and recorder of unit 164 of surface equipment 18. It is,
therefore, apparent that a neutron-gamma ray log is obtained,
providing useful information regarding the earth formations traversed
by the bore hole. Of course, other types of logs may be derived. For
example, tube 15 may be a proportional counter lined with a
hydrogenous material or a boron compound. In that way, a
neutron-neutron log may be obtained. Moreover, with suitable
provisions, a combination neutrongamma ray and neutron-neutron log is
possible. Alternatively, by pulsing generator 14, for example, through
the medium of the application of control pulses of positive polarity
at lead 122 and gating detector 15, an activation log may be obtained.
Since automatic controls are provided for gas pressure and neutron
flux, the neutron generator embodying the present invention may be
reliably oPerated during an entire logging run. The operator need not
be concerned with any critical and continuous adjustments to the
equipment.
In general. by reason of the particular and unique construction of the
generator 14. as evident in Fig. 2, a relatively rugged device is
possible, Moreover. generator 14 has a configuration small enough so
that it is adapted to the elongated, small-diameter, cylindrical
housing suitable to be passed through conventional oil-filled bore
holes.
The remainder of the bore hole apparatus may be readily accommodated
to the size and ruggedness requirements of equipment adapted to be
passed through a bore hole.
Therefore, the well logging apparatus embodying the present invention
meets all requirements of logging service.
It will be observed that since the ion beam traverses an opening
defined by deflection plates 42-45 and opening 38 of probe 36, these
electrodes may be operated as an electrostatic lens. Thus, by
adjusting the potential impressed between probe 36 and deflection
plates 42-45. the area of the ion beam at target layer 41 may be
controlled to achieve a desired focus. For example, the beam may be
spread so that a relatively large target area is bombarded with
deuterium ions. In this way, the rate at which the tar-' get is
depleted of tritium may be reduced as compared with a narrow beam
impinging on a small area of the target.
In Fig. 5 of the drawing, there is illustrated one form of circuit
which may be employed for output control circuit 123 of Fig.
1A. Pulses from unit 131 are applied over lead 133 to a pulse
transformer 170, the secondary winding of which is connected to an
integrator 171 which develops a negative potential at an output lead
172 that is connected to the control grid of a triode-type electron
discharge device 173. The remain- ing output lead 174 of integrator

27. 171 is connected by a cathode resistor 175 to the cathode of device
173. Lead 174 is also connected to lead 124 and thus extends to the
negative terminal of medium-voltage power supply 115 (Fig. 1B). An
anode load resistor 176 connects the anode of device 173 to tap 117 of
voltage divider 116, thereby providing a source of anode-cathode
current for device 173. Lead 122, which extends to the tap of
transformer 121, is connected to the junction of anode load 176 and
the anode lead of device 173.
Circuit 123 further includes another electron discharge device 177 of
the triode4ype having its cathode tied to the cathode of device 173
and its anode connected by an anode load resistor 178 to lead 125. Its
control grid is connected to the movable tap of a potentiometer 179.
One terminal of the resistance element of potentiometer 179 is
connected to lead 124 and the other terminal is connected by a
dropping resistor 180 to lead 125.
To condition the circuit for operation, the positive grid bias on
triode 177 is adjusted by means of potentiometer 179 to achieve an
anode-cathode current resulting in a desired voltage drop across
cathode resistor 175.
Since resistor 175 is common to the cathode circuits of triodes 173
and 177, this voltage provides a negative grid bias for triode 173.
Preferably, triode 173 is biased for essentially linear operation over
its grid voltage versus anode current characteristic through out an
expected range of applied grid voltages.
In response to the pulses applied over transformer 170, integrator 171
develops a negative voltage having an amplitude proportional to the
pulse-rate. Accordingly, if the pulse rate increases, the absolute
value of the negative voltage applied over leads 172 and 174 to the
grid circuit of electron tube 173 increases. As a result, the anode
current of tube 173 flowing through anode resistor 176 decreases and
the voltage drop across this resistor decreases, thereby reduced ing
the potential between leads 122 and 125.
Conversely, a decrease in pulse rate results in a decrease in the
negative voltage applied to the grid circuit of device 173. This
causes the voltage drop across anode load resistor 176 to increase and
the voltage between leads 122 and 125 increases,
Since the voltage between leads 122 and 125 determines the average
value of the-voltage between deflection plates 42-45 and cathode plate
23, it is evident that the average voltage at the deflection plates
varies indirecdy with the intensity of the generated neutron flux to
achieve automatic output control as described hereinbefore. Obviously,
the quiescent or stable operating flux may be adjusted by means. of
potentiometer 179.
If desired, a third filament (not shown) composed of zirconium may be

28. mounted within envelope 19 (Fig. 1B and Fig. 2). Such a filament may
be arranged to operate at a temperature in the neighborhood of 1300cm.
and serve as a getter, chemically reacting with gases. The output
control circuit just described may be suitably modified so that when
the neutron flux output of generator 14 drops below a prescribed
limit, the getter filament is energized.
A circuit suitable for use as pressure-control circuit 120 (Fig. 1A)
is illustrated in Fig.
6. This circuit comprises a diode rectifier 185 having its cathode 186
connected to the lead 119 which extends to anode 26 of ion source 20.
Its anode 187 is connected to housing 13 and its filament 188 is
energized from power leads 113 and 114 via a stepdown tran,sformer
189. The turns ratio of step-down transformer 189 is arranged so that
the filament voltage for diode 185 is below the normal rated value.
Inasmuch as diode emission is thus limited, the maximum current which
may be drawn in the anodecathode circuit for ion source 20 and diode
185 is fixed.
A relay coil 190 is interposed in the circuit between the anode 187 of
diode 185 and housing 13. This relay coil is associated with a pair of
normally closed contacts 191 connected to power lead 113 and to the
lead 139 which extends to transformer 137.
A pair of normally open contacts 192 are connected to power lead 113
and to lead 140 which extends to transformer 138. Contacts 192 are
associated with a relay coil 193 that is shunted across diode 185. A
current limiting resistor 194 is interposed in series relation with
coil 193.
The operation of circuit 120 may best be understood by reference to
Fig. 7 in which a curve 198 represents the current versus voltage
characteristic for diode 185 and the curve 199 represents the
voltage-current characteristic for ion source 20. It is evident that
although the voltage across diode 185 may increase beyond the voltage
designated E, the current flowing through the diode remains
substantially constant. This characteristic is useful in maintaining
the ion concentration within ion source 20 fixed despite pressure
variations which might occur within envelope 19, as will be apparent
from the following discussion.
As seen in Fig. 7, diode characteristic curve 198 intercepts load line
199 for source 20 at a voltage designated Vl. Accordingly, the voltage
drop across diode 185 is Vl volts and the voltage across ion source 20
may be defined as the voltage V (at which load line 199 intercepts the
voltage axis) minus Vl. If the pressure within envelope 19 increases,
the ion source load line shifts to the position de- signated 199'. Due
to the constant-current feature of diode 185. the intercept of load
line 199' and curve 198 occurs at voltage 071, that is greater in

29. magnitude than voltage V. In other words, the voltage drop across
diode 185 increases and the voltage drop across ion source 20
decreases to the value V2-V1,. Since an increase in pressure is
accompanied by a decrease in the applied voltage to ion source 20, the
ion concentration remains essentially unchanged.
On the other hand, a decrease in gas pressure shifts the ion source
load line to the position 199" which intercepts curve 198 at voltage
Vl", smaller than V1. Since the voltage across ion source 20 thereby
increases to the value V,-V,", such a decrease in pressure does not
materially reduce the ion concentration in the ion source.
As long as the current flowing in the anode-cathode circuit of diode
185 produces a voltage above voltage E, the current through coil 190
is sufficient to produce a magnetic field which maintains normally
closed contacts 191 open. Accordingly, no current is supplied to
filament 83. At the same time, the voltage across diode 185 may be too
low to cause coil 193 to affect normally open contacts 192 which thus
remain open and no current is supplied to absorber filament 85.
If, for any reason, the current in the diode circuit drops below the
value at which voltage E occurs, coil 190 is effectively de-ener
gized, thereby closing contacts 191 and current is supplied to
filament o3, which, as pointed out hereinbefore, is associated with
deuterium emitting material 84. Hence, gas is emitted and gradually
the pressure in envelope 19 rises. The current flowing through ion
source 20 and diode 185 thus increases until the current at which
voltage E occurs is obtained. At this point relay coil 190 is again
energized. If pressure in envelope 19 increases to a preselected value
above that at which voltage E occurs, say to the value at which
voltage V1, is obtained, the voltage across diode 185 is sufficient
for the field of coil 193 to close contacts 192 and filament 85 is
energized. It absorbs gas and when the pressure drops, coil 193 is
effectively deenergized. Therefore, automatic pressure control is
provided by circuit 120.
Of course, if desired, a third filament (not shown) designed to react
chemically with gases may be paralleled with filament 85 for getter
operation.
In Fig. 8, the details of ion pump 93 are illustrated. It comprises a
plurality of annular or rieg-like electrodes 200 supported in
longitudinally spaced relation within conduit 90 by respective ones of
a plurality of leads 201 which pass through and are fused or sealed to
the wall of conduit 90. Thus. an electrical connection may be made
between each of the rings 200 and a respective one of a plurality of
successive taps 202 of a voltage divider 203. having one terminal '04
connected to housing 13 and its remaining terminal 205 connected to
the negative terminal of medium-voltage power supply 1 15. Of course,

30. any desired number of rings 200 may be employed together with a
corresponding number of taps 202 on divider 203.
A rod-like, axially extending electrode 206 is supported within
conduit 90 by end connections 207 and 208. one of which, 207, is
connected to terminal 204 so that electrode 206 is at a positive
potential with respect to all of the ring electrodes 200.
A solenoid 209 is wound on the exterior wall of conduit 90 and is
arranged so that it is spaced from and electrically insulated from
each of leads 201. Solenoid 209 may comprise any desired number of
layers, although only one layer is illustrated for the sake of
simplicity of representation. One of its end leads is connected to
ground at terminal 204 and the opposite end lead is connected to the
positive terminal of power supply 132. Thereby, the solenoid may be
energized and produces an axial magnetic field within conduit 90.
Electrons emitted by each of the ring electrodes 200 are accelerated
towards the rod electrode 206 due to the positive potential impressed
thereon. As a result of the influence of the magnetic field produced
by sole- noid 209, these electrons travel in spiral paths toward the
rod electrode and ionizing collisions with gas molecules occur. The
electrode spacings and voltages are selected to promote strong
ionization, and since the ring electrodes 200 are at succesilv elv
hither negative potentials relative to a direction line from the lower
end to the upper end of pump 93, positive ions are urged in the
direction of arrow 94. Accordingly, a net transfer of gas, as positive
ions, occurs in addition to the flow of neutral molecules that takes
place simply due to the flow of positive ions.
In many instances, there may be a sufficient flow of ions out of the
upper end of tube 90 into envelope 19 so that ion source 20 is not
needed. Consequently, pump 93 serves both as a pump as well as an ion
source, thereby improving efficiency of ion production. Obviously, the
elimination of ion source 20 greatly simplifies the overall
construction of neutron generator 14.
The cross-sectional view of Fig. 9 illustrates the interior details of
monitor or de tector tube 127. The tube comprises an outer
electrode-envelope 210 constructed of a cylinder of electrically
conductive material such as thin steel which is permeable to neutrons.
Envelope 210 is surrounded by an insulating sleeve 211 which also is
permeable to neutrons. For example, a fluoro-carbon, commonly referred
to as teflon, may be employed for this purpose.
An electrode 212 of rod-like configuration is supported coaxially
within envelope 210 and the envelope is sealed and filled with argon
or a suitable combination of argon and methane gases.
In order that detector 127 may have directional properties, a layer of
hydrogenous

31. material 213, such as polyethylene, is disposed. on the interior
surface of envelope 210.
This layer extends for less than one half the circumference of the
envelope on a side thereof in the general vicinity of neutron
generator 14. To improve the temperature characteristics of the
polyethylene lining, it may be exposed to intense radiation prior to
the incorporation of detector 127 within housing 13.
In operation, some of the fast neutrons emanating from generator 14
travel in the general direction designated 214, and enter hydrogenous
material 213. Some of these react with the hydrogenous material to
produce recoil protons which cause ionization of the gas within
envelope 210. Thus, pulses representing the generated neutron flux are
produced by detector 127.
On the other hand, high energy neutrons travelling from formations 11
or from fluid
12 of bore hole 10 penetrate the detector in any of the general
directions 215, 216, or 217, other than direction 214. Since the
portion of the detector on which such neutrons are incident is not
provided with hydrogenous material, no recoil protons are produced.
Moreover, after traversing the interior of the detector and striking
hydrogenous layer 213, any resulting protons have maximum energies
directed away from the gas within envelope 210 and do not trigger the
detector. It is, therefore, evident that detector 127 is directional
and output control circuit 123 is responsive only to the neutrons
emanating from neutron generator 14.
If desired, a layer of hydrogenous material may be supported within
housing 13 at the opposite side of generator 14, with respect to
detector 127, so that high energy neutrons returning from formations
on the opposite side of the bore hole may be absorbed to prevent them
from being counted.
In order to achieve symmetrical bombardment of the formations by the
neutrons emanating from target 40 of generator 14, monitor 127 may be
mounted above or below the generator. Of course, for such an
arrangement, suitable shields of hydrogenous material may be provided
for the monitor.
As an alternative to the use of polyethylene in the layer 213,
zirconium in which hydrogen is absorbed may be employed. This is
possible since the bonding of hydrogen with the zirconium is stable at
high tempera tures.
To obtain a different type of log, monitor
127 may be modified and mounted within a shoe that is biased relative
to housing 13 so as to be maintained against the sidewall of the bore
hole. The modified monitor is arranged in a well-known manner to be
only responsive to thermal neutrons arriving at the sidewall from the

32. formations. Since the generated flux of high energy neutrons is under
the control of the monitor, the flux of amount of evaporated metal is
extremely small, compared with the weight of the target. Hence, its
collection on the inner wall of the glass envelope and on the outer
sur
faces of metal components does not undesir
ably affect the operation of the neutron gen
erator.
It is, Therefore, evident that during the op
eraticn of the neutron generator, fresh
hydride is continuously exposed as tritium is consumed and high
operating efflciency is maintained for extended periods of time.
Although lithium has been proposed for
the alternative target construction, other
metals having the desired properties may be utilized. For example.
other alkali metals, such as sodium, potassium, rubidium and caesium.
have melting temperatures lower than their hydrides and thus may be
suit
able.
If desired, an auxiliary electrode may be
associated with the target 40, 41 and im
pressed with a potential of negative polarity relative to the target,
such as may be obtained by means of a bias resistor in circuit with
the target. This electrode thus operates to suppress secondary
electrons at the target and, in the embodiment of the invention
including lithium in the target, serves as a sink for lithium that is
freed after deuterium-tritium reactions.
Moreover, target cooling may be achieved by introducing a tube (not
shown) into conical section 39 of the envelope to a point adjacent cap
40. Thus, a coolant, such as compressed air, may be applied via the
tube to cap 40 and the coolant then may pass between the outer surface
of the tube and section 39 on its way to a suitable heat-transfer
device (not shown).
Obviously, additional information from equipment within housing 13 may
be sup plied to indicators at the surface of the earth by conventional
multiplexing techniques
without requiring the use of more conductors in cable 17. For example,
a detector of slow neutrons may be provided so that simultaneous
neutron-gamma and neutron-neutron logs may be obtained. Also. a
suitable voltmeter may be provided for monitoring the output voltage
cf power supply 156. Specifically. time-shan"g may be utilized for
mul- tiplexing or a i plantom circuit may be set up between cajole
conductors 134 and 153 and ground. Alternatinelvz a balanced phantom"
arrangement m.y be provided by using conductors 134 and 153 and

33. conductors 104. 106 and 105. 107.
What we claim is:
1. A neutron generating system comprise ing a sealed envelope cont.
inina a gas and including an ion-source section and an
accelerating-gap section. a target for intercepting the accelerated
ions of the gas. said target being adapted to react with the ions of
the gas to produce neutrons. characterised by a sealed off conduit
connecting said ionsource section with said accelerating-gap section
and constituting a closed and sealed loop between said sections of
said envelope.
2. A neutron generating system according to Claim 1, wherein said
system further comprises a pump associated with said conduit to effect
a flow of said gas through said conduit in a direction from said
accelerating-gap section toward said ion-source section.
3. A neutron generating system according to Claim 2, wherein said pump
includes a discharge chamber a plurality of electrodes distributed
along a path through said chamber and means for producing an ionic
discharge in said chamber and for energizing said electrodes to effect
said flow of said gas.
4. A neutron generating system substantially as described herein with
reference to the
accompanying drawings.
* GB784642 (A)
Description: GB784642 (A) ? 1957-10-16
An improved lamp housing
Description of GB784642 (A)
PATENT? SPECIFICATION
7841 A 42 Date of filing Complete Specification: Feb 8, 1956.
Application Date: Feb 25, 1955.
No 5775/55.
Complete Specification Published: Oct 16, 1957.
Index at acceptanace:-Class 75 ( 4), C( 2 A 3: SH 2: 11).
International Classification:-F 21 b.

34. COMPLETE SPECIFICATION
An improved Lamp Housing We, BELSHAW AND COMPANY LIMITED, a British
Company, and LEONARD ALBERT Bl SHOP, a British Subject, both of 39,
Victoria Street, London, S W 1, do hereby dedare the invention, for
which we pray that a patent may be granted to us, and the method by
which it is to be performed, to be particularly described in and by
the following statement: -
The present invention relates to an improved lamp housing of a form
enabling the lighting effect to be changed from a condition of maximum
illumination to a condition of subdued illumination.
The lamp housing according to the invention is particularly suitable
for use in the illumination of individual beds in hospital wards.
The improved lamp housing according to the invention comprises a
hollow elongated box-like structure which, when in position for use,
is closed at its ends and has a closed front wall, upper and lower
walls each provided with a window, shutters within the box-like
structure movable between positions in which the windows in the upper
and lower walls are uncovered and positions in which the window in the
upper wall is covered and the window in the lower wall is partly
covered, and a common control accessible from the exterior for
effecting simultaneous movement of the shutters.
The box like structure is preferably shaped so that, when the lamp
housing is in use, the lower wall thereof or at least the portion of
said lower wall containing the window is inclined downward in a
direction away from the said closed front wall.
The rear of the box-like structure may be open and formed for flush
engagement with an attachment to a wall or preferably to the edges of
a lamp-holding box or wall box of conventional form which is itself
attached to a wall.
A lamp housing particularly suitable for use in the illumination of
individual beds in (Price 3 s 6 d l hospital wards will now be
described by way of example with reference to the accompanying
drawings in which: Fig 1 is a perspective view of a completely 50
assembled lamp housing having the upper window partially broken away
in order to expose the inside of the housing.
Fig 2 shows the inside of the shutter-encasing portion of the lamp
housing 55 Fig 3 is a section on the line III-III in Fig 1 and, Fig 4
is a perspective view of one form of lamp holder and bracket for use
in the lamp housing 60 A completely assembled lamp-housing as shown in
Fig 1 comprises a shutter casing 11 fixed to a wall box 12 by means of
screws 13, the wall box 12 carrying a bracket 14 on which is mounted a
lamp holder 15 hold 65 ing an electric light bulb 16.
The shutter enclosing part of the casing 11, of which the inside is
shown in Fig 2, comprises a box-like structure having two flat

35. parallel end walls 18 and 19, a horizon 70 tal upper wall 21, a
vertical front wall 22 and a bottom wall 23 diverging from the upper
wall 21 in the rearward direction, the junction of the front and
bottom walls being formed by a merging curved portion 24 The 75
box-like structure is open at the rear (Fig 2) and flanges 28 and 29
are provided on the rear edges of the end walls 18 and 19 for the
attachment of the shutter casing 11 to the wall box 12 80 The upper
and lower walls 21 and 23 are formed with rectangular apertures 31 and
32 The apertures are covered by windows 33 and 34 of glass, "Perspex"
(Registered Trade Mark) or other light transmitting 85 material, the
upper window being transparent and the lower window being translucent
or light diffusing The windows 33 and 34 may be mounted so as to
provide narrow gaps between their edges and all or some of 90 the
sides of the walls 21 and 23 of the shutter casing, to permit air
circulation between 2 784,642 the exterior and interior for cooling
and ventilation, such narrow gaps being shown at 25 and 26 in Fig 3 at
the shorter sides of the walls 21 and 23.
S Shaped plates 36 and 37 are fixed by means of screws 38 and 39 to
the side walls 18 and 19 respectively The plates 36 and 37 have
flanges 41 and 42 respectively formed on their upper and lower edges
which serve to hold windows 33 and 34 against the upper and lower
walls 21 and 23 of the shutter-enclosing part 11 of the casing.
Fixed between the plates 36 and 37, and extending along the length of
the box like structure, are two rods 44 and 45 to which are hingedly
connected substantially rectangular shutters 46 and 47 respectively
The lower shutter 47 is formed with a central recess 48 in its free
edge which pel-mits a subdued light to pass through the translucent
window 34 when the shutter 47 covers window 34 as shown in Fig 3.
A further rod 49 passes through holes formed in the side walls 18, 19
and the plates 36, 37 and extends along the length of the box-like
structure beyond the outside surface of the walls 18 and 19, the rod
49 carrying at its ends externally accessible control levers 51 and 52
respectively.
A bell-crank lever 53 (Fig 3) is rigidly fixed to rod 49 and is
coupled, by means of links 54 and 55, to lugs 56 and 57 provided on
the backs of the shutters 46 and 47, respectively.
In operation, when the bell crank lever 53 is moved in the clockwise
direction about the axis of the rod 49, as seen in Fig 3, with the aid
of one or other of the external levers 51 or 52, the shutters 46 and
47 are simultaneously moved away from the windows 33 and 34 but
movement of the crank lever 53 in an anti-clockwise direction moves
them into the position shown in Fig 3, i e covering the windows 33 and
34.
The bulb-holder bracket 14 is held resiliently in the wall box 12 by

36. means of tongues 62 to 67 which bear against the inside surface of
parallel walls 68 and 69, thus facilitating positioning of the
electric light bulb so 16 anywhere along the length of the wall box
12, the position of the bracket 14 depending on the shape and size of
the bulb 16 used.
Knock-outs 71 are provided in the walls of box 12 to permit a hole
being made at a suitable place for the entry of an electric cable as
shown at 72 (Fig 1).
In use, the wall box 12 is preferably secured in the recess of a wall
over a hospital bed and the position of the bulb holder bracket 14 is
adjusted so that the light bulb 16 lies centrally within the wall box
12 The shutter casing 11 is then screwed to the base box 12 by means
of the screws 13 and the lamp housing is ready for use When it is
desired to use full illumination, the shutters 46 and 47 are moved
away from the windows 33 and 34 by means of the external control lever
51 or 52 thus permitting full light, diffused by window 34, to fall on
the patient's bed and full light passing through window 33 to be 70
projected towards the ceiling where it is reflected to illuminate the
ward When only an observation light is required, that is to say for
example, a light for observing a patient during the night, the
shutters 46 and 47 are 75 turned into the position shown in Fig 3 i e.
to cover windows 33 and 34 In this position of the shutters only a
small amount of light passes through the recess 48 and that light
diffused by the window 34, is directed 80 onto the patient's bed When
complete darkness is required the light may be switched off by means
of a switch not shown.
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